@acer 

Yes your first code do the work (sorry). I have not understand the effect of the frequency.

I am very happy, thank you 

@acer : Thanks for the answer:

I want to plot a function where the axis of abscisse theta is the radius R (for example cos(theta)). As in the figure below in red.

Download plot.mw

@Kitonum Thank for the answer.

But, I want plot the function cos(theta) where the axis theta of the function is represented by the contour (perimeter) of radius R (not inside the circle). I do not know if my explanations are good.

@acer 

Thank you

The command

plots:-matrixplot( Y, heights=histogram, gap=0.5,
                   color=((x,y)->1-y/3+0.2),
                   orientation=[-55,55,0], labels=["","",""] );

 is what I want.

@Markiyan Hirnyk 

I have Maple 18 and I can not find the command.

dataplot does not exists in Maple 18

@Markiyan Hirnyk @Carl Love 8142: Thank you

Yes, OrthogonalExpansions package can be used to determine 2D Fourier series coefficients. Now, I can read the help from Maple18.

From DiscreteTransforms, are matrices (3) and (4) represent the coefficients of 2D Fourier expansion ?  The matrices are the Fourier transform and we need to do an inverse Fourier transform to get the coefficients ?

Can you help me to plot the 2D Fourier expansion function issued from Discrete Transforms with the original function f(x,y).

Thank you

I am using OrthogonalExpansion currently. It can not give the Fourier expansion from 2D Fourier transform.

I want to use 2D Fourier transform to obtain the coefficients of the 2D Fourier expansion of a surface as done in http://www.mapleprimes.com/questions/121551-Fourier-Serie-And-Discrete-Fourier-Transform for curves.

Thank you.

Thank you.

@Joe Riel 

Thank you for your answer.

Yes this work around solution allows end time simulation completed to 0.04s

But It is not a good solution. How to explain this add on to my students and for me too 

Is there an other way ?

Thanks you again

@Joe Riel 

Thank you for your answer.

Yes this work around solution allows end time simulation completed to 0.04s

But It is not a good solution. How to explain this add on to my students and for me too 

Is there an other way ?

Thanks you again

mli_pont1.msim

Thank you for the answer.

But, The result seem to me wrong. Could you see the code attached ?

Thank you for the answer.

But, The result seem to me wrong. Could you see the code attached ?

Thanks for all,this last way is the best

Thank you